sup people!!

Discussion in 'Introduce Yourself' started by ceedantech, Apr 15, 2014.

  1. ceedantech

    ceedantech New Member

    Hi there, I'm chris and i live here in pittsburg CA .I just built my first motorized bicycle (friction drive).

    here is my mobike info.

    Marin MTB (i don't have any idea what model my bike is).
    GP460 chun yang (r460) its a 45.7cc engine.
    DAX Motor mount from RoadBugmotors. (not Advertising)

    and it runs 43 mph in 3/4 throttle.

    IMG_0037.jpg IMG_0062.jpg IMG_0064.jpg :devilish::devilish:
     

  2. butterbean

    butterbean Well-Known Member

    Your speedo is set to km/h, not mph.
     
  3. ceedantech

    ceedantech New Member

    yeah... im just using my phone to convert kmh to mph.. 71.3 kmh = 44.3 mph.
     
  4. Fabian

    Fabian Well-Known Member

    Going downhill...
     
  5. ceedantech

    ceedantech New Member

    nope i did that on flat surface.. its not a big deal for me coz i dont know how accurate my speedometer is.
     
  6. butre

    butre Well-Known Member

    I don't believe for a second you did 44.3 mph with a friction drive setup.
     
  7. ceedantech

    ceedantech New Member

    yeah next time i'm gonna try to make video and use garmin gps (i guess its more accurate than speedometer). :devilish:
     
  8. ceedantech

    ceedantech New Member

  9. butterbean

    butterbean Well-Known Member

    If you are using an electronic speedo, and you've programmed it correctly (measured your wheel diameter from the outside of your tire and input that instead of the measurements provided with the instructions), then your speedo could be within +/- 3mph. If you have a smartphone, you can download a speedometer app that uses gps. Many of them are free. But yeah, I don't believe 43 on a friction drive. I don't believe anything over 35 on a stock china 2 stroke either. I'm not trying to call you a liar, I just don't think your speedo is programmed correctly.
     
  10. Fabian

    Fabian Well-Known Member

    :iagree: 101%

    I am suspicious at anything over 25mph on a stock Chinese bicycle engine.
     
  11. LR Jerry

    LR Jerry Well-Known Member

    What size wheels do you have?
     
  12. LR Jerry

    LR Jerry Well-Known Member

    Here is the specs on the OP engine:

    Specifications:

    45.7cc High Output Race Engine
    Horsepower 4.20HP at 18,000 RPM
    Torque = 2.315 lb-ft (0.32 kg-m) at 8,000 RPM
    Includes fabric air filter w/ anodized aluminum protective shroud

    The kit he's using has 2 roller sizes 1" and 1.25". If the stats on the engine are true at 3/4 throttle that would be 13500 rpm which would propel the bike 40 mph using 26" wheels and the 1" roller.

    This seems like way to powerful of an engine for a friction drive system. Tires wearing out quickly. Potential blowouts I don't even want to think about that one at 40+ mph.
     
    Last edited: Apr 17, 2014
  13. ceedantech

    ceedantech New Member

    I have 26" wheels, 1.25" spindle(roller) and i used kenda tire 26x1.95.
     
  14. LR Jerry

    LR Jerry Well-Known Member

    Your speedometer setting for a 26" wheel is 2075. At 3/4 throttle (13500 rpm) using the 1.25 roller your speed would've been 49.7 mph. This is way too much engine for a friction drive system.

    I noticed you have rim brakes and the engine is mounted in the rear. On a bicycle the majority of the weight is on the rear wheel. On hot summer days your rear tire will have an extremely high heat build up. The tire will also wear out really fast as well. You are really going to be prone to a blow out.

    I'd suggest converting your engine over to a chain driven system. You may even want to do a whole new build with the engine. Then you could put a mid grade performance engine on the friction drive bike sell it to help pay for your high performance bike.
     
    Last edited: Apr 18, 2014
  15. darwin

    darwin Well-Known Member

    Get a Kevlar lined tire for the rear, that's a powerful setup for a FD you have there. Especially if you have a steel gnarled roller driving it.
     
  16. butre

    butre Well-Known Member

    I wouldn't put one of those on an f/d but I'd absolutely love to have one for a frame mount race bike
     
  17. LR Jerry

    LR Jerry Well-Known Member

    That's the way I feel too Butterbean. A chain driven system would be the best way to go with such an engine. That much power on a friction drive setup is down right dangerous.
     
  18. butre

    butre Well-Known Member

    Mine did around 34 with the stock engine and a 40 tooth sprocket. With a low compression head I could see 25 being the maximum but with the higher compression angled plug head I had no problem getting to 30+ mph, though it did take me forever to get there
     
  19. LR Jerry

    LR Jerry Well-Known Member

    One does have to question what is so special about a Chun Yang engine to give it such a high performance.
     
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